Kel'Thuzad:It is a vast, demonic army that has consumed countless worlds beyond our own. Now, it comes to set this world to the flame. Our master was created to pave the way for its arrival. The dreadlords were sent to make sure that he succeeded.

Arthas:So the plague in Lordaeron, the citadels of Northrend, the slaughtering of the elves... It was all just to prepare for some huge demonic invasion?

Kel'Thuzad:Yes. In time, you will find that our entire history has been shaped by the coming conflict. Now come; we have much work to do.